Yes, there is. However, how you go about doing this, will vary greatly based on the version of ArtRage you are using.
It should be a simple task with ArtRage Studio Pro, because Pro has the Adjust Colors panel (Edit > Adjust Layer Colors). The panel allows one to do everything from hue shifting, and color saturating, to contrast and brightness (see image below).
If you don't have ArtRage Studio Pro, you can still alter the layers/image, by using some workarounds. For example, if you wanted to brighten the image, you can create a new layer, paint it white (either using the Fill tool in Studio, or just painting over it with a tool on a smooth canvas in AR 2.6). Then, by Right clicking the layer in the layer panel, and changing the Blend Mode option to Overlay, one may change the brightness of the image (or filled in area of the canvas). The brightness may then be lowered, by lowering the opacity of the white filled layer. Alternatively, a contrast effect can be attained, by also doing this with a black color filled layer (so you would have both a white and black filled layer, using the Overlay blend mode). The amount of color the image has, can be filtered by filling a layer with white, and setting it's Blend Mode to Color. Again, changing the opacity of the filled layer, will alter the amount of change taking place. If one wished to change the hue of the image, filling a new layer with the color of choice, and using either the Hue or Color Blend Modes, will shift the colors, and again, changing the opacity will alter the amount of change that occurs.
Nothing is easy to the unwilling.